(Mg1-xSrx)2SiO4∶(Eu3+,F-)荧光粉的物相及光谱

Phase Constitutions and Luminescent Spectra of (Mg1-xSrx)2SiO4∶(Eu3+,F-) Phosphors

采用高温固相法在空气氛围下在1 150℃制备(Mg 1-x Sr x)2SiO 4(x=0~1)粉末。物相分析表明,随着Sr离子含量由小到大,(Mg 1-x Sr x)2SiO 4基质晶相组成将发生如下变化:γ-Mg 2SiO 4、β-Mg 2SiO 4混合相(x=0)→α-Sr 2SiO 4、β-Sr 2SiO 4、γ-Mg 2SiO 4、β-Mg 2SiO 4、Sr 3MgSi 2O 8混合相(0.2≤x≤0.8)→α-Sr 2SiO 4和β-Sr 2SiO 4混合相(x=1);当x=0.2时主晶相为高温β-Mg 2SiO 4,而在x=0时主晶相为低温γ-Mg 2SiO 4。紫外发光照相和光谱表明,当x=0.2时,(Mg 1-x Sr x)1.96 SiO 4∶0.04(Eu 3+,F-)红光发射亮度最大。进一步晶体结构分析发现Sr离子可以固溶入β-Mg 2SiO 4使得β-Mg 2SiO 4更为稳定,同时晶格略微增大;化学配比为(Mg 0.8 Sr 0.2)2SiO 4粉末在1 250℃煅烧可以得到平均粒径为21.68μm的单相β-Mg 2SiO 4粉末。对于单相(Mg 0.8 Sr 0.2)2-y SiO 4∶y(Eu 3+,F-)系列荧光粉,其XPS分析表明Eu离子以三价进入晶格;光谱分析表明在365 nm和254 nm激发下,有595,615(主峰),655,705 nm红光锐峰发射(对应5D 0→7F n,n=1,2,3,4);且y=0.04为最佳铕离子掺杂浓度(此时其量子效率、寿命均达到最大);基于Blasse理论可判断铕离子间能量传递方式为基于辐射跃迁的电四极-电四极作用。

(Mg 1-x Sr x)2-y SiO 4(x=0~1)powder was prepared at 1 150℃by high temperature solid-state method.As Sr ion content in matrix increasing,the phase constitutions change fromγ-Mg 2SiO 4,β-Mg 2SiO 4 mixture(x=0)toα-Sr 2SiO 4,β-Sr 2SiO 4,γ-Mg 2SiO 4,β-Mg 2SiO 4,Sr 3MgSi 2O 8 mixture(0.2≤x≤0.8),then toα-Sr 2SiO 4,β-Sr 2SiO 4 mixture(x=1).Furthermore,when x=0.2,the main phase is β-Mg 2SiO 4,while x=0,the main phase isγ-Mg 2SiO 4.UV light excitation and luminescent spectra analysis show(Mg 0.8 Sr 0.2)1.96 SiO 4∶0.04(Eu 3+,F-)has been picked out as the best red phosphor composition among(Mg 1-x Sr x)1.96 SiO 4∶0.04(Eu 3+,F-).Sr ion would go intoβ-Mg 2SiO 4 crystal lattice,and makes the phase more stable.When the annealing temperature reaching at 1 250℃,the powder has the composition as(Mg 0.8 Sr 0.2)2SiO 4 would be single phase asβ-Mg 2SiO 4.(Mg 0.8 Sr 0.2)2-y SiO 4∶y(Eu 3+,F-)series(~21.68μm)have red-band emission peaks at 595,615(main),655,705 nm(related to 5D 0→7F n,n=1,2,3,4)under 365 nm or 254 nm excitation,and the most suitable Eu 3+doping amount is 4%(the quantum yields and lifetime both reaching to maxium value among the series).Based on Blasse theory,the main energy transfer mode for activators should be the four electric dipoles(q-q).